242 Bulletin 176. 



Crude carbolic acid is another favorite ingredient in washes. 

 Hale says it is tlie " meat '' of his wash, on the theory that its odor 

 is offensive to the moths. In our experience in combating the peach- 

 tree borer or any other insect, we have seen little or no evidence that 

 substances having offensive odors had any repellant effect in keeping 

 the insect away from the food-plant of its progeny. Asafetida did 

 not in our experiments, and we do not believe that any of the effect- 

 iveness of tarred jpaper protectors was due to their odor, for others 

 get just as good results from newspapers ; they form a mechanical 

 and not an odorous barrier to the insect. Hence, we do not believe 

 that carholic acid is a useful ingredient of washes. 



Most, perhaps all, of the washes act simply as a preventive, 

 meclianical coating over the bark to keep the newly-hatched borers 

 out. Such substances as raupenleim, dendrolene, and gas tar seem 

 to be ideal washes, but the two first usually kill young trees, and the 

 last also has a similai" reputation in some localities, although we saw 

 no evidence to indicate that tar was injurious to well-established 

 young peach trees. Perhaps some one can so modify these ideal 

 washes as to retain their effectiveness as a preventive and yet elimi- 

 nate their plant-injuring qualities. Future compounders of washes 

 should work along this line. 



We think that most of the above generalizations regarding washes 

 may also apply to washes designed to prevent the work of the apple- 

 tree borer. 



When to apply washes or other preventive measures. — In New 

 York the applications should be made between June 15th and July 

 1st, and they should remain in perfect working order until October 

 1st. In Canada, July 15th will usually be soon enough to make 

 applications, and they should last until November. In the South, 

 the applications should be made in April and they will apparently 

 have to last for three or four months. Read the detailed discus- 

 sions of the different methods for instructions how they are to be 

 applied. 



Final conclusions. — In our four years of warfare against the 

 peach-tree borer we have been thoroughly convinced that it is a 

 very difficult insecc enemy to control. No method of lighting it 

 has yet been devised by which the peach-grower can hope to get a 



